This invention relates to an adjustable hospital bed having a lifting system for elevating or lowering the bed in either a horizontal or a tilted position, while at the same time permitting independent height adjustment at each end.
Adjustable hospital beds are usually vertically movable so that the mattress supporting structure may be established at a selected desired height, within a range of permissible heights, from the floor. The lowermost level is most convenient when a patient is entering or leaving the bed. On the other hand, the uppermost height is generally preferred for examination and treatment of the patient. In addition, many adjustable hospital beds may be tilted or canted to either the trendelenburg position or to the reverse trendelenburg position. In the trendelenburg or shock position, the entire mattress supporting structure is tilted between 10.degree. and 20.degree. from horizontal so that the patient's head lies below his or her legs. In the reverse trendelenburg or drainage position the patient's head is above his or her legs.
To maximize the vertical adjustment range or travel in prior hospital beds, without sacrificing stability, the mattress supporting structure is customarily mounted on a movable upper frame which interconnects, via head and foot elevating linkage systems, to a fixed lower base frame located close to the floor. The elevating linkage systems are actuated to either lift or lower the upper frame, and consequently the mattress supporting structure, as desired. For trendelenburg or reverse trendelenburg positioning, the hospital bed usually must first be placed at a predetermined height and then actuated to the desired tilt position.
The hospital bed of the present invention is capable of assuming not only all of the various positions of the prior hospital beds but in addition a variety of other positions are obtainable. Moreover, this is achieved with a unique construction which is considerably simpler and more reliable than those of the previously developed hospital beds. A salient feature of the invention is the capability of actuating the bed to its trendelenburg or reverse trendelenburg position from any level. The bed may be tilted in either direction, and to any tilt angle, regardless of the height of the bed at the time. This feature, among other advantages, results in a significant time saving when adjusting the bed.